Recording system for simultaneously projecting photographic images with a recorded commentary

ABSTRACT

Method and system for a simultaneous projection of photographic images associated with a recorded commentary. Electrical signals coming from the audio spectrum representing the commentary are recorded and a series of control pulses having a given carrier frequency and occuring at predetermined intervals are superimposed on the signals. The pulses are modulated with a signal having a frequency different from the carrier frequency. A switching means is actuated by detected and amplified modulating signals for actuating a photographic image changing device and short-circuiting a filter connecting a reading device to a loudspeaker.

United States Patent Halley RECORDING SYSTEM FOR SIMULTANEOUSLYPROJECTING PHOTOGRAPHIC IMAGES WITH A RECORDED COMMENTARY Claude AnsbertGaston. Gustave Pierre Halley, Colombes, France Paul Claude, MarieTouvier-Berthet, Lyon, France, a part interest Aug. 27, 1968 lnventor:

Assignee:

Filed:

Appl. No.:

Foreign Application Priority Data Sept. 4, 1967 France ..l19825 US. Cl...179/100.2 S, 179/l00.l PS Int.Cl. ..Gllb 23/30,Gllb27/30,Gllb31/00Field of Search ..l79/100.1 VC, 100.2 S, l00.2 MD, 179/1001 TC;340/174.l K, 174.1 C

[ 51 Jan. 25, 1972 [56] References Cited UNITED STATES PATENTS 2,780,6792/1957 Vandivere "179/1002 S 2,787,669 4/1957 Flan et al. 179/10013,305,645 2/1967 Nisbet ..179/l00.2 S 3,420,966 1/1969 Wright....179/1002 S 3,482,038 12/1969 Warren 1 79/1002 Ml PrimaryExaminer-Bernard Konick Assistant ExaminerA1fred H. EddlemanAttorney-Wenderoth, Lind & Ponack 57 ABSTRACT 4 Claims, 5 DrawingFigures RECORDING SYSTEM FOR SIMULTANEOUSLY PROJECTING PHOTOGRAPHICIMAGES WITH A RECORDED COMMENTARY The present invention relates to theprojection of photographic images by means of, for example, a projectorcomprising an automatic image-changing device, the images beingprojected simultaneously with a recorded spoken commentary or othermusical accompaniment, the automatic control being achieved by means ofpulses superimposed on the electrical spectrum recorded from saidcommentary.

A method for recording such a commentary is known in which a certainfrequency of the recorded electrical spectrum is eliminated and a pulsehaving the same frequency is recorded at predetermined intervals, thatis, wherever it is desired to change from one photographic image toanother during the reading or reproduction of the recording.

A drawback of this method is that, when reading the recorded commentary,the audio spectrum is mutilated since a given frequency has beeneliminated from the recorded spectrum and is not reproduced for theaudience.

The object of the invention is to remedy this drawback.

The invention provides a recording method for the simultaneousprojection of photographic images associated with a recorded commentary,said method comprising recording the electrical signals coming from theaudio spectrum representing the commentary, superimposing on saidsignals a series of control pulses which have a given carrier frequencyand occur at predetermined intervals, and modulating said pulses with asignal having a frequency different from the carrier frequency.

Said modulation can be a frequency, amplitude or phase modulation.

The various types of modulation can be effected simultaneously, themodulation frequencies then having if desired different values.

According to a particular feature of the invention, whose purpose is torender the control pulses as inaudible as possible, the amplitude ofeach of said control pulses follows a decreasing law.

Further features and advantages of the invention will be apparent fromthe ensuing description with reference to the accompanying drawing.

In the drawing:

FIG. 1 is a simplified diagram of a recording system for carrying out afirst example of the method according to the inventron;

FIG. 2 is a simplified diagram of a reading system for readingrecordings made by means of said method;

FIG. 3 illustrates an embodiment of a reading system showing theutilization of a recording having a plurality of series of controlpulses;

FIG. 4 is a diagram illustrating a particular feature of the operationof a relay, this figure facilitating the explanation of the switch shownin FIG. 5, and

FIG. 5 is a diagram of one embodiment of a switch shown in FIG. 1.

FIG. 1 shows a system for recording in accordance with a first exampleof the method according to the invention. This system comprises atransducer 1 for converting audio vibrations-produced by the reading ofa commentary for example adapted to accompany the projection of a seriesof diapositive images or lantern slides-into electrical signals. Thistransducer is connected to a recording device 2 which can operateaccording to any principle, such as for example that of magnetic tapes,phonograph discs, or optical films.

The recording system also comprises an oscillator 3 delivering a carriersignal of any electrical frequency (Fp).

The oscillator 3 is modulated by a second oscillator 4 producing amodulating signal whose electrical frequency (Fm) is necessarilydifferent from the carrier frequency (Fp). Thus, the signal issuing fromthe oscillator 4 modulates, that is, varies the phase, frequency oramplitude of the signal from the oscillator 3. This group of signals isapplied to the input of the recording device 2 through switch means 5whereby it is possible to apply only constant duration pulses of themodulated signal. The latter, which is mixed with the signals from thetransducer, therefore forms the complex signal which is recorded by therecording device 2 on a support suitable for this operation such as, forexample, a magnetic tape, a photograph disc, an optical film, or thelike.

The frequencies employed by the oscillators 3 and 4 can have any values.However, they cannot be identical. By way of example, and in order topermit the reproduction by means of conventional reading or reproducingapparatuses, the carrier frequency Fp could be chosen to be 8,000 Hz.and the modulating frequency Fm to be 50 Hz. Thus, the modulation of Fpcould be chosen to be one of amplitude by the frequency Fm. FIG. 2 showsa reading system for the signal recorded by the recording system shownin FIG. 1.

This system comprises a reading apparatus proper 6, such as a recordplayer if the recording has been effected on a phonograph disc forexample, a tape recorder if a magnetic tape has been used, etc. Theoutput of the reading apparatus 6 is connected to a filter 7 whoseresonance is tuned to the frequency of 8,000 Hz. in the chosen example.

This filter consists of an inductance coil S1 and a capacitor C1. It hasa maximum impedance at its resonant frequency and is therefore capableof opposing the transmission to a loudspeaker 8 connected thereto,frequencies of value Fp, namely 8,000 Hz. in this example. Now, thefilter 7 is short circuited by a switch 9 the action of which will bedescribed hereinafter. The speaker 8 therefore receives all the recordedsignals with elimination of no frequency and complete fidelity of therecording is therefore achieved.

Further, the output of the reading apparatus 6 is connected to a filter10 whose resonant frequency is tuned to the frequency Fp (8,000 Hz.).This filter 10 consists of an inductance coil S2 and a capacitor C2 andis connected in such a manner that it has a minimum impedance at itsresonant frequency and therefore only transmits a narrow band offrequencies centered on the frequency Fp to an amplifier 11 connectedthereto. These signals are thus amplified at the output of the amplifier11 and applied to a filter 12 also tuned to the frequency Fp, thisfilter consisting of an inductance coil S3 and a capacitor C3, wherebyto improve the selectivity of the system, that is the capacity toseparate the frequencies applied to the filter 10. The signals offrequency Fp available on the filter 12 are received by a winding 13 andthen transmitted to an amplitude detector 14 whose function is toeliminate the carrier frequency Fp and make the modulating signal Fmappear. This signal of frequency Fm, namely 50 Hz. in the presentlydescribed example, is then applied to another amplifier 15 which isconnected to a filter 16 consisting of an inductance coil S4 and acapacitor C4. This filter 16 is tuned to the value of the frequency Fm.The signal of frequency Fm available at the filter 16 is received by awinding 17, coupled to the winding S4, and thereafter rectified by adiode 18, that is converted into a DC voltage which is again amplifiedby an amplifier 19 and applied to an electromagnet 20 which it iscapable of energizing.

The electromagnet 20 actuates the switch 9 and another switch 21. Whenclosed by the action of the electromagnet 20, the switch 21 controls animage-changing device 22 of a projector (not shown), which is thedesired function in the presently described example. When opened by theaction of the electromagnet 20, the switch 9 opens the short circuit ofthe filter 7 and the latter then opposes the transmission to the speaker8 of the signals which had initiated the control or actuation of thedevice 22. These signals are consequently not perceived by the audience.

This system operates in the following manner:

If a signal of frequency Fp is read by the reading or reproducingdevice, there are two possibilities:

I. This signal comes from a sound of the commentary and must notinitiate the actuation of the image-changing device 22; it musttherefore be perceived by the audience.

Being of suitable frequency, this signal is not stopped by the filter10, is amplified by the amplifier 11 and available on the filter 12. Itis received by the winding 13 and transmitted to the diode 14. But as itdoes not have the modulating frequency Fm, its detection does not resultin a suitable signal capable of passing through the amplifier 15 and nosignal appears on the filter 16 and nothing can be received by thewinding 17. No voltage is applied to the diode 18 and no voltage istherefore transmitted to the amplifier 19 which cannot energize theelectromagnet 20. The switch 21 remains open and does not actuate thechanging device 22. The switch 9 remains closed and still short circuitsthe filter 7 and consequently the sound of frequency Fp can bereproduced by the speaker 8.

2 This signal comes from a pulse of the oscillator 3 (FIG. 1) modulatedby the oscillator 4 and must therefore actuate the changing device 22without being perceived by the audience.

As this signal is of suitable frequency it is not stopped by the filterl and is amplified by the amplifier 11 and available on the filter 12.It is received by the winding 13 and transmitted to the diode 14. Asthis signal comprises the frequency Fm its detection results in a signalof frequency Fm at the input of the amplifier and this amplified signalappears at the filter I6 and is received by the winding 17. The signalis rectified by the diode 18 and a DC voltage appears at the input ofthe amplifier 19. When amplified, this voltage is applied to theelectromagnet 20 which it actuates. The switch 21 closes and actuatesthe changing device 22, the switch 9 opens and causes the filter 7 tooperate and the latter opposes the transmission to the speaker 8 of thissignal of frequency Fp. The signal consequently remains inaudible to theaudience since it is not reproduced by the speaker.

The actuation of the changing device 22 therefore requires a doubleinformation, namely the reading of a frequency Fp and the modulation ofthis frequency by another frequency Fm. The application of either ofthese frequencies alone results in no reaction. The application offrequency Fp along resumes the first possibility described hereinbeforeand a signal having the frequency Fm alone cannot pass the filter 10.

It should be mentioned that the simultaneous application of two distinctfrequencies, one of value Fp and the other of value Fm cannot satisfythe complete detection. These frequencies must be in close relationshipaccording to the type of detection employed. This relationship is amodulation of the amplitude of frequency Fp by the frequency Fm, whichis the relationship chosen in the example shown in FIG. 2 (diode 14), amodulation of the frequency Fp by Fm, or a modulation of the phase of Fpby Fm.

It should also be noted that the frequency Fm cannot be reproduced bythe speaker 8 since this frequency does not appear at the output of thereading apparatus 6. The appearance of frequency Fm essentially impliesa detection of Fp appropriate to the modulating method employed whenrecording in accordance with the system shown in FIG. I.

It will be understood that the reading system described hereinbeforeemploys a recording consisting of a complete audio spectrum having atcertain intervals a pulse of frequency Fp modulated by a frequency Fm,these pulses resulting in the changing of diapositive images or lanternslides. The frequency Fp is therefore only eliminated from the audiospectrum perceived by the audience when a control pulse is produced. Inpractice, this spectrum can be considered as being fully transmitted.

However, it is possible to record several types of control pulsesmodulated with distinct frequencies, which serve in the reading systemafter filtering in particular filters, too obtain several controlsignals, these pulses for example starting up a second projector orlighting up the projecting room. These pulses can of course be modulatedin different ways.

One embodiment of such a reading system is shown in FIG. 3. In thisdiagram, the reproducing channel and the filters and relay contacts havebeen omitted for reasons of clarity.

The control signals received in a reading device 30 are transmitted to afirst filter of frequency Fp, namely filter 31. Its output signal istransmitted, detected and filtered in three separate channels, 32, 33and 34 (Fml, Fm2, Fm3) controlling relays 35, 36 and 37 respectively,the latter serving to control a first projector, start a secondprojector when the first has used up a batch of diapositive images orlantern slides and light up the room at the end of the commentary.

It will be observed that the carrier frequency is modulated in amplitudeby the frequency Fml and modulated in frequency by the frequencies Fm2and Fm3. A discriminator 29 detects the latter frequencies.

With reference to FIG. 4, which has been given only by way of example, afew properties of an electromagnetic relay will now be recalled.

A relay R is fed by a battery B through a potentiometer P. Thepotentiometer varies the intensity of the energization current of therelay R. It is observed that the intensity required for holding therelay exceeds the intensity, when the energization is no longersufficient, at which the relay is released. Consequently, the relay canbe operated by energizing it with a pulse of given current density(point x). It is observed that the relay remains energized with a muchsmaller intensity (point y)- This feature of relay operation can beemployed in the method according to the invention. Indeed, according toa particular feature of the invention, the purpose of which is to renderthe control pulses as inaudible as possible when reproducing, theamplitude of each of these pulses follows a decreasing law. The controlrelay 22 (FIG. 2) is energized at the start of the pulse and maintainedin this position by the rest of the pulse until the amplitude at whichthe energization can no longer be maintained is reached.

It will be understood that, in this way, the pulse, while it has anaction identical to that of pulses of constant amplitude, is lessperceptible to the audience, on one hand because the pulse appears to beof shorter duration to the listener, and, on the other hand, because asthe ear is very sensitive to sudden variations in the perceivedspectrum, one of the variations has become very regular, namely thevariation which puts a stop to the pulse.

One embodiment, by which the invention is not intended to be limited, ofa device for obtaining control pulses having a decreasing law is shownin FIG. 5. This device is no other than a special form of the switch 5shown in FIG. 1 and comprises a capacitor 38, one terminal of which isearthed and the other connected to the junction point of two resistors39 and 40. A pushbutton 41 is connected in parallel with the capacitor38. The resistor 40 is connected in series with a polarization battery42 whose positive terminal is earthed. The resistor 39 is connected tothe input 43 of the device (connected to the output of the oscillator 3shown in FIG. 1) and to the grid of a triode 44 connected as anamplifier. The anode of the triode is connected in series with an anoderesistor 45 and a battery 46, and to the output terminal 47 of theswitch, which is connected to the recording device 2 (FIG. 1).

While the pushbutton 41 is open, the triode 44 is turned off by thepolarization voltage supplied by the battery 42, the capacitor 38 beingcharged. The signal from the oscillator 3 (FIG. 1) therefore cannot passthrough the triode and reach the recording device 2.

When it is desired to record a control pulse, that is, change from onediapositive image or lantern slide to another, the pushbutton 41 isactuated in such a manner that the capacitor 38 is dischargedinstantaneously. The triode can therefore amplify the signal applied toits grid, the latter having the potential of the earth. However, thecapacitor is charged progressively so that the triode is polarizedprogressively until turned off. The output pulse therefore follows adecreasing law.

Note that a recording effected in accordance with the method of theinvention can be read or reproduced if desired with a reading orreproducing system adapted to reproduce recordings made in accordancewith the conventional method described hereinabove.

However, in this case, one condition must be satisfied when recording.The electrical signal must be slightly attenuated at the carrierfrequency Fp so that a sound, normally emitted during the commentary atthis frequency and having a sufficiently high amplitude level, does notaccidentally cause the image-changing relay to respond. Further, thepulses must be recorded by means of the device described with referenceto FIG. 5 so as to render them as little audible as possible. Theimage-changing relay is then energized by the start of the pulse andwill remain energized practically until its disappearance. Themodulation frequency Fm in this case is not detected.

However, it will be observed that the level of the control pulse can belower in this case, and consequently less audible, if its modulation iseffected in amplitude for a given sensitivity of the control relay.Indeed, as the modulation frequency is not perceptible in the speaker ofthe conventional system since no detection is effected, it is howeversuperimposed on the DC current resulting from the detection of thesignal Fp of the control pulse. The pulse of the current which actuatesthe control relay is an undulating current whose crests are higher thanin the case where unmodulated pulses would be recorded (the case of aconventional recording method). Consequently, the recording according tothe invention can be read or reproduced in conventional reproducingsystems, it being possible for the control pulses to have a much higheramplitude at the frequency Fp than they have in recordings made inaccordance with the conventional recording method. The pulses willtherefore be less audible.

An example, by which the invention is not intended to be limited, willnow be given of a recording made by the method according to theinvention. This recording can be reproduced with the conventionalreproducing system and with the system according to the invention, thecontrol part of which is shown in FIG. 3.

The recording made with a system including the switch shown in FIG. 5 ismade under the following conditions:

The sound channel employed has a range of 20-50,000 Hz. The images arechanged by control pulses obtained from a signal of 7,000 Hz. which is100 percent amplitude modulated by a frequency of 50 Hz. The pulsesexhibit a decreasing amplitude. Changing from the first projector to thesecond projector, after the batch of diapositive images or lanternslides of the second projector has been used up, is effected by means ofa control pulse of 7,000 Hz. which is frequency-modulated by a signal of100 Hz. and amplitude modulated at 50 Hz. A control pulse of 7,000 Hz.frequency-modulated by a signal of 400 Hz. is recorded for automaticallylighting up the projecting room.

During the reproduction in a reading or reproducing system designed inaccordance with the conventional method, the control pulses of 7,000 Hz.modulated with a signal of 50 Hz. change the images, the control relayof the image-changing device being energized at the start of the pulseby the maximum amplitude and maintained in its energized position by therest of this control pulse of decreasing amplitude. The pulses of 7,000Hz. frequency-modulated at 100 Hz. and at 400 Hz. are ineffective since,as they have not been modulated in amplitude, their amplitude isinsufficient to actuate the relay.

It should be mentioned that the frequency of 7,000 Hz. cannot reach theaudience since a filter is provided in the reproduction channel.

During the reproduction in a system according to FIG. 3, the pulsescontrol respectively:

at 7,000 Hz. with amplitude modulation 50 Hz. (Fml), the

relay 1; image changing,

at 7,000 Hz. with frequency modulation (Fm2) the relay 2; the connectionand starting up of the second projector, the first projector being putout of operation,

at 7,000 Hz. with frequency modulation at 400 Hz. (Fm3) the relay 3alone is energized and the lights in the projecting room are turned on.

Although specific embodiments of the invention have been described, manymodifications and changes may be made therein without departing from thescope of the invention as defined in the appended claims.

Having now described my invention, what I claim is new and desire tosecure by Letters Patent is:

l. A system for reproducing recordings made, in a recording system for asimultaneous projection of photographic images associated with arecorded commentary, such a recording comprising simultaneously recordedthereon, electrical signals coming from the audio spectrum representingsaid commentary and superimposed to said audio spectrum signals, aseries of control pulses of a given carrier frequency and occuring atpredetermined time intervals, said control pulses being modulated withsignals the frequency of which is different from said carrier frequency,said reproducing system comprising a sound channel having a readingdevice, a loudspeaker connected to said reading device by means of afilter tuned to said carrier frequency, in order to stop the same, firstfiltering and amplifying means for passing and amplifying only thecarrier frequency signals, second filtering, detecting and amplifyingmeans connected in series with said first filtering and amplifying meansfor passing, filtering, detecting and amplifying only said modulatingfrequency signals, switching means actuated by said detected andamplified modulating frequency signals, for actuating a photographicimage changing device and for short circuiting said filter connectingsaid reading device to said loudspeaker upon the absence at the outputof said reading device, in said audio spectrum signal of said modulatedpulse signals in order to pass to the loudspeaker the part of the audiospectrum corresponding to the frequency of said pulses and forconnecting said loudspeaker filter upon the presence in said audiospectrum of said modulated pulse signals in order to prevent said pulsesignals to reach said loudspeaker.

2. A system as claimed in claim 1, comprising a series of detecting andamplifying means having outputs respectively connected to distinctswitching means, each of said detecting and amplifying means beingcapable of producing a signal as a function of the appearance of amodulating frequency corresponding to the respective switching means.

3. A system as claimed in claim 1, wherein said switching means comprisea switch actuated by a relay connected to the output of said secondfiltering, detecting and amplifying means, said switch having a firstcontact for actuating said photographic image-changing means and asecond contact for short circuiting said filter connecting saidloudspeaker to said reading device.

4. A system as claimed in 2, wherein said distinct switching meanscomprise switches actuated by respective relays connected to the outputsof said respective detecting and amplifying means.

1. A system for reproducing recordings made, in a recording system for asimultaneous projection of photographic images associated with arecorded commentary, such a recording comprising simultaneously recordedthereon, electrical signals coming from the audio spectrum representingsaid commentary and superimposed to said audio spectrum signals, aseries of control pulses of a given carrier frequency and occuring atpredetermined time intervals, said control pulses being modulated withsignals the frequency of which is different from said carrier frequency,said reproducing system comprising a sound channel having a readingdevice, a loudspeaker connected to said reading device by means of afilter tuned to said carrier frequency, in order to stop the same, firstfiltering and amplifying means for passing and amplifying only thecarrier frequency signals, second filtering, detecting and amplifyingmeans connected in series with said first filtering and amplifying meansfor passing, filtering, detecting and amplifying only said modulatingfrequency signals, switching means actuated by said detected andamplified modulating frequency signals, for actuating a photographicimage changing device and for short circuiting said filter connectingsaid reading device to said loudspeaker upon the absence at the outputof said reading device, in said audio spectrum signal of said mOdulatedpulse signals in order to pass to the loudspeaker the part of the audiospectrum corresponding to the frequency of said pulses and forconnecting said loudspeaker filter upon the presence in said audiospectrum of said modulated pulse signals in order to prevent said pulsesignals to reach said loudspeaker.
 2. A system as claimed in claim 1,comprising a series of detecting and amplifying means having outputsrespectively connected to distinct switching means, each of saiddetecting and amplifying means being capable of producing a signal as afunction of the appearance of a modulating frequency corresponding tothe respective switching means.
 3. A system as claimed in claim 1,wherein said switching means comprise a switch actuated by a relayconnected to the output of said second filtering, detecting andamplifying means, said switch having a first contact for actuating saidphotographic image-changing means and a second contact for shortcircuiting said filter connecting said loudspeaker to said readingdevice.
 4. A system as claimed in claim 2, wherein said distinctswitching means comprise switches actuated by respective relaysconnected to the outputs of said respective detecting and amplifyingmeans.